This application references all material contained in the patent titled Multichannel Data Compressor, U.S. Pat. No. 4,995,036, issued Feb. 19, 1991. Embodiments of the apparatus disclosed and claimed in the referenced patent application constitutes certain of the elements of the combination of the present invention. The information included in the referenced patent applications has been included for technical reference purposes and is not to be regarded as essential subject matter on which the claims of the present application depend for support or upon which the application depends for adequate disclosure of the invention.
The transform scaling data compression and image processing apparatus is a data compressor and image processor for a data transmission system wherein data representing elements of a video image are mathematically transformed, and a certain number of resulting transform coefficients are eliminated according to an established threshold. The reduced number of transform coefficients are then transmitted by a communication link to a scaling filter, which expands the received data to reestablish the original number of transform coefficients. The latter are inversely mathematically transformed to acceptably reproduce the original data representing elements of the video image. An image processor is also included to identify objects represented by the video image.
Past efforts to improve the efficiency of data transmission have included such methods as increasing the rate at which data is sent. As the rate increases, however, the required bandwidth of the transmission system also increases. One method for avoiding prohibitive bandwidth problems is to digitize and compress data, thereby reducing the total number of bits of information, before it is transmitted.
Schiller, in U.S. Pat. No. 4,723,298, teaches an image compression apparatus that reduces the number of elements representing an image by dividing the total number of picture elements in the image into units each containing rows and columns of individual picture elements; assigning to each unit a single binary value, which is a weighted function of the binary value of each of the picture elements in the unit; further dividing the total number of units into rows and columns of sets; and assigning to each set a single binary value, which is a weighted function of the binary value of each of the units in the set.
Grayson, in U.S. Pat. No. 4,783,841, teaches a data compressor apparatus that compares data blocks of decreasing size with a group of patterns relevant to each size. If a match is found, the matched data block is represented on an input signal by a code identifying the pattern. If a lower size limit is reached with no matches being found, the data itself is applied to the output signal.
Sato, et al., in U.S. Pat. No. 4,797,741, teach an information signal transmission system that divides an original image information signal consisting of a number of picture elements arranged in rows and columns into a plurality of small blocks, each consisting of rows and columns of picture elements, to provide a plurality of compression modes of different information compression rates.
Shimoni, et al., in U.S. Pat. No. 4,809,350, teach a data compression system that compresses data representing the difference between uncompressed data and predicted further data by encoding the difference data using a string length code arrangement for the most prevalent difference data, encoding the second most prevalent data with a replacement code that is the shortest, and encoding the sequentially next most prevalent difference data with the shortest replacement code not previously used.
Methods and apparatuses for changing the scale or size of images are disclosed by U.S. Pat. Nos. 4,790,028; 4,809,083; and 4,809,345. Methods and apparatuses using mathematical transforms for recognizing and processing images are disclosed in U.S. Pat. Nos. 4,590,608; 4,621,337; 4,703,349; 4,744,659; 4,764,973; 4,764,974; and 4,817,176. Apparatuses using neighbor transforms and matrix operators for recognizing and processing images are disclosed in U.S. Pat. Nos. 4,630,308; 4,641,351; 4,703,513; 4,776,025; 4,736,439; and 4,805,228.
In present practice, mathematical transform techniques are typically used to facilitate image compression in the following manner. Images are focused on a matrix of cells, each representing a picture element, or pixel, constituting a camera retina. The cells might be, for example, photoelectric or photodiode-type devices that produce electrical voltages proportional to the intensity of light striking them. The cells are then scanned by a video circuit to produce an analog video signal. The analog video signal is digitized, and a portion of the digitized signal representing one video frame is accumulated in a frame storage matrix, or frame buffer, comprising the same number of cells, in the same relative positions, as the camera retina. Each cell of the frame storage matrix comprises a digital word containing bits of binary data representing levels on a gray scale.
A two-dimensional, mathematical transform is performed on the stored signal representing the video frame values, and the electrical representations of the transformed values are stored in a transform frame storage matrix. The transformed values represent transform coefficients.
Relatively acceptable picture quality can often be maintained even if half to three quarters of the transform coefficients are deleted; therefore, data compression can be achieved by deleting a portion of the transform coefficients. The means for doing this have been the subject of much of the literature on image compression by transform methods; but it may be said that, in essence, this is done by deleting all coefficients having values below a certain threshold level.
The remaining transform coefficient values may then be transmitted by way of a pulse code modulation (PCM) signal to a receiver and stored in a receiver frame storage matrix. The transform coefficient values are arranged in the same relative positions as they were when stored in the transform frame storage matrix. The electrical representations of zero are placed in cells that would have been occupied by transform coefficients that were deleted.
An inverse mathematical transform is performed on the stored transform coefficient values, and the electrical representations of the inversely transformed values are stored in a receiver inverse transform frame storage matrix. The values represented are similar to those stored in the frame storage matrix, and their digital electrical representations are converted to an analog video signal. The analog video signal is then applied to a video screen to create an acceptable likeness of the original video image.
The Multichannel Data Compressor is a data compressor for a data transmission system wherein the data from a plurality of data sources is compressed and multiplexed to generate a compressed data word that significantly increases the sampling rate of the plurality of data sources over the sampling rate if the data from each data source was transmitted in its entirety.
The Multichannel Data Compressor has a plurality of data latches for temporarily storing the data generated by each data source and a plurality of difference circuits, one for each data source, which subtract the data stored in the data latches from the next subsequent data value generated by the data sources to generate a difference data value. A plurality of summing circuits sum the difference data values to generate a plurality of composite data values. A selector switch transfers the composite data values or selected current data values to a multiplexer when the magnitude of at least one of the composite data values exceeds a predetermined value. The multiplexer formats the received data into a predetermined format, converts it to a serial format, then forwards the data to a transmitter for transmission. A receiver system has a multichannel data decompressor that regenerates, in response to a received data transmission, data as originally generated by the data sources.
Data compression has been known in the art to reduce the bandwidth of the transmission system or to increase the sampling rate of the data to be sent. As data requirements become higher and higher, data compression remains one way in which more data can be transmitted without having to increase the bandwidth of the transmission system. Eng et al. in U.S. Pat. No. 4,593,318 discloses a technique for time compressing television signals in which the transmission comprises a line, frame, or field, as received plus two other lines, frames or fields as differential signals. Eng et al. also teaches multiplexing the output of three different video sources so that the output of the three different video sources can be transmitted in the same time span normally required to transmit the same data, as originally generated from a single video data source.
Cavanaugh, in U.S. Pat. No. 4,099,202, Brown et al. in U.S. Pat. No. 4,237,484, Shimoyama et al. in U.S. Pat. No. 4,542,406 and Tu in U.S. Pat. No. 4,544,950 teach the multiplexing of the digital audio and video data for simultaneous transmission, rather than transmitting them on separate sidebands as done with commercial television transmissions.